﻿using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using Common.Utilities;

namespace Workflows.Components.Entities.Distances.VectorDistance
{
    public class EuclideanDistanceCalculator:IAttributeDistanceCalcutor
    {
        #region Implementation of IAttributeComparer

        /// <summary>
        /// load dictionary into memory or read config settings from file
        /// </summary>
        public void InitInMemorySettings()
        {
            
        }

        /// <summary>
        /// return similarity score in [0,1]
        /// 0 indicate no similarity or null match
        /// 1 indicate perfect match
        /// </summary>
        /// <param name="attrValue1"></param>
        /// <param name="attrValue2"></param>
        /// <param name="result"></param>
        /// <returns></returns>
        public double Compare(object attrValue1, object attrValue2, ref MatchResult result)
        {
            result = MatchResult.NullMatch;
            if (attrValue1 == null || attrValue2 == null)
                return 0;

            string strVal1 = attrValue1.ToString();
            string strVal2 = attrValue2.ToString();
            if (strVal1.Length == 0 || strVal2.Length == 0)
                return 0;

            string[] vector1 = StringUtil.Split(strVal1);
            string[] vector2 = StringUtil.Split(strVal2);

            List<string> unionVector = new List<string>();
            foreach (string feature1 in vector1)
            {
                unionVector.Add(feature1);
            }
            foreach (string feature2 in vector2)
            {
                if (!unionVector.Contains(feature2))
                {
                    unionVector.Add(feature2);
                }
            }
            double sumSq = 0;
            foreach (string feature in unionVector)
            {
                double freq1 = 0;
                if (vector1.Contains(feature))
                    freq1 = 1;
                double freq2 = 0;
                if (vector2.Contains(feature))
                    freq2 = 1;
                sumSq += Math.Pow(freq1 - freq2, 2);
            }
            double euclideanDistance = Math.Sqrt(sumSq/unionVector.Count);
            return 1 - euclideanDistance;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="entity1"></param>
        /// <param name="entity2"></param>
        /// <param name="attrMetaData"></param>
        /// <param name="result"></param>
        /// <returns></returns>
        public double Compare(Entity entity1, Entity entity2, AttributeMetaData attrMetaData, ref MatchResult result)
        {
            
            Debug.Assert(!string.IsNullOrEmpty(attrMetaData.AttributeName));

            string attrName = attrMetaData.AttributeName;
            object attrValue1 = null;
            object attrValue2 = null;
            if (entity1.ComparableAttributes.ContainsKey(attrName))
                attrValue1 = entity1.ComparableAttributes[attrName];
            if (entity2.ComparableAttributes.ContainsKey(attrName))
                attrValue2 = entity2.ComparableAttributes[attrName];
            return this.Compare(attrValue1, attrValue2, ref result);
        }

        /// <summary>
        /// argument to bind attribute name
        /// </summary>
        public string[] ArgumentNames
        {
            get
            {
                return new string[] {"Features (vector)"};
            }
        }

        private Dictionary<string, string> _ComparerSettings;
        public Dictionary<string, string> ComparerSettings
        {
            get
            {
                return _ComparerSettings;
            }
            set
            {
                this._ComparerSettings = value;
            }
        }
        #endregion
    }
}
